Bell STiR+ Radar+Laser (9500ci), now horn causing Laser falsing

[HankLloydRight]

Just as the title states.. I bought a used STiR+ on ebay, had it professionally installed, and it's working great except for one problem...

Every time I honk the horn, it triggers a false laser alert -- usually a rear alert, but sometimes a front alert.

A page on the Bell website states the following:

Laser Falsing
It is unusual to get false laser warnings. Some cars and other electronics put out more RF interference than others and that interference may cause a false laser alert when certain devices are used. Although rare, using the horn, windshield wipers, or accelerating, can generate RF interference in some vehicles. Does it do the same thing in other cars/trucks? New cell phones, new cars with laser adaptive cruise control, and the wind-shear equipment at some major airports can also cause false laser alerts.
If you are experiencing false laser alerts of this type, please call our Customer Service Department at 800-543-1608 and they will give you a repair authorization number and instructions on how to return to us. We will be able to make modifications to your detector that will help.

Since I bought it used, I suspect they won't be keen on fixing the unit as mentioned. Also, the way that text is written ("same thing in other cars..."), it sounds like it's more for portable radar+laser units and not the hardwired STiR/9500ci type units.

Has anyone seen and/or solved this on their own before? I don't know if the RF interference from the horn emanates from the horn itself, or from other electronics in the Model S... and do the laser heads themselves receive the RF interference, or is it the main controller/head unit for the STiR+?

I'm considering trying to re-route some of the wires if they run near the horn (I had the STiR+ professionally installed).. or maybe just replacing the stock Tesla horn?

Any suggestions? Thanks.

 

[efusco]

How often do you honk your horn?
Maybe, if the laser falsing due to honking is that much of an issue you should consider honking less. I don't think I honk once a month.

 

[HankLloydRight]

How often do you honk your horn?
Maybe, if the laser falsing due to honking is that much of an issue you should consider honking less. I don't think I honk once a month.

Oh, I totally agree! In fact, it was about a week after the install that I honked the horn. I don't use the horn all that much anyway... but I do use it to fend off a$$holes and bad drivers.

But it's *very* annoying when I do have to use the horn, to expect the loud and abrupt laser alerts.

 

[Chris TX]

Mine does the exact same thing. I just thought it was the EMI from the horn piezos. I installed my STiR on my own, so I don't know if they'll do the modification for me. I bet there's some kind of shielding they put in place. Have you tried contacting them? Do you know what module gets modified?

Alright, here's the deal:

I called and spoke to them. They said the interface (part that everything plugs into) needs to have an RF filter modified. Since I'm 26 days outside my 1 year warranty, it's going to cost me $49.95 to have the modification done which includes shipping back to me. They said it will take 5-7 business days to get it back to me. Until then, I need to be super careful driving. ;-)

 

[HankLloydRight]

I called and spoke to them. They said the interface (part that everything plugs into) needs to have an RF filter modified. Since I'm 26 days outside my 1 year warranty, it's going to cost me $49.95 to have the modification done which includes shipping back to me. They said it will take 5-7 business days to get it back to me. Until then, I need to be super careful driving. ;-)

Wow, great info, thanks!

Now I just have to find out where the installers put the control unit, and how easy/hard it will be to extract and send back in. I'm going to see if I can "live with it", but at least I know the annoyance is a $50 cost to fix (in theory).

 

[HankLloydRight]

Well, earlier today I emailed Bell with the same questions, and I just got their (differing) reply:

Unfortunately with the horn there is no repair available to make the unit not false on laser when honked. Some of the other issues like acceleration can be corrected as indicated, but the horn cannot. The only way to eliminate that falsing is to change the horn in the vehicle.

I apologize for the inconvenience.

So Chris, if you do send back your unit for the $50 refit, please let us know if it works and stops the laser falsing. Thanks.

 

[Chris TX]

Well, earlier today I emailed Bell with the same questions, and I just got their (differing) reply:

So Chris, if you do send back your unit for the $50 refit, please let us know if it works and stops the laser falsing. Thanks.

Hmm, now I wonder if this will work. The guy said it would fix the problem when they modified an RF filter. I wonder if there is some shielding that can be placed on or near the horns/relay to help with this. I know the relay does emit a bit of EMI when engaged. I don't want to spend $50 just to find out nothing is fixed. Does anyone know where the horn relay is on a Model S?

 

[HankLloydRight]

Is it the horn, or the horn relay that's emitting the RF? Or both?

I've been thinking of replacing the horn with an electronic horn (think of the possibilities!!), but if it's the relay causing the RF, I'd have to tap into the relay to trigger the electronic horn.

 

[Chris TX]

Is it the horn, or the horn relay that's emitting the RF? Or both?

I've been thinking of replacing the horn with an electronic horn (think of the possibilities!!), but if it's the relay causing the RF, I'd have to tap into the relay to trigger the electronic horn.

The simple test would be to disconnect the horns, push the horn button to actuate the relay, then see if the false laser is shown. However, the lack of load from the missing horns might not generate enough spark upon engagement, now that I think about it. Maybe I should connect some 12V halogen bulbs in place of the horns to generate the proper load. It's too cold to experiment right now and we have errands to run, so I won't be heating up the garage.

 

[HankLloydRight]

I've been thinking of replacing the horn with an electronic horn (think of the possibilities!!),

BTW, my idea for an electronic horn is to be able to sound different sounds based on how long the horn is pressed.

-- One very short/intermittent horn tap: Play low volume "Pedestrian" warning sound (I want to have "The Jetson's" car sound).

-- Between that duration and 5 seconds, full car horn sound.

-- Any longer than 5 seconds -- diesel train horn (vey loud).